Pump systems such as those used in various industrial, commercial, and domestic applications, such as oil refineries, water supply, gasoline supply, and the like, may include two or more pumps to maintain the supply and level of fluid. Generally, one or more pumps in the pump system is a redundant pump and is used when additional supply is required, in case of a fault in a running pump, or to relieve the primary pump. Therefore, the use of multiple pumps increases overall system reliability and extends the time period during which any one pump may be kept in service. In most applications, redundant pumps are not instrumented with a speed detector. Further, for pump systems having a large number of pumps, it is time-consuming to manually analyze whether a pump is running or stopped. Seismic transducers may be used to monitor pump casing vibration and to determine the pump state (i.e., running or stopped).
Various methods may be used to perform data validation, calculation, analysis, and detection of specific events and malfunctions in machines. An existing method compares the overall (peak-to-peak or direct) vibration level observed by a seismic transducer associated with the pumps against a pre-configured on-state threshold value (i.e., a value at or above which the pump is in a running state) to determine whether the pump is running or stopped. Typically, manual analysis is done on historical data of vibration measurements collected over a period of several months to set the on-state threshold value. Therefore, various man hours are required to collect data and configure the on-state threshold values of the pumps.
Generally, multiple pumps may be installed on a common foundation. In this case, appropriate setting of the on-state threshold value based on seismic data becomes even more difficult and time-consuming due to the required detailed analysis of the historical data. Moreover, vibrations from a running pump may be transferred to a stopped pump. Subsequently, the stopped pump may have substantially higher vibration level than expected for a pump in a stopped state. Thus, simple identification of overall vibration levels for a pump does not necessarily indicate that a higher level of vibrations is for a running state. Moreover, a lower level of vibration in a stopped pump may be due to environmental vibrations, even when all pumps on the common foundation are stopped. Further, there may be change in the higher or lower vibration of the running pump due to the changing pump conditions, such as bearing deterioration or imbalance. As a result, the on-state threshold value that had been set previously may be no longer accurate, and using it may lead to erroneous results.
Accordingly, there is a need for methods and systems for monitoring operating states of pumps. There is a further need for automatic determination and calculation of on-state threshold of vibrations of pumps and for updating the on-state threshold of vibrations in real time or near real time for more accurate pump diagnostics. Additionally, there is a need for methods and systems that calculate the threshold values on-line by using the recently collected data.